This invention relates to grid-type suspended ceilings such as are currently in widespread use in modern building structures, for example, large public buildings such as shopping centers, theaters, garages, and the like, and relates more specifically to apparatus which facilitates installation of junction boxes which are capable of reliably hanging lighting fixtures and appliances which are of considerable weight.
Suspended ceilings comprised of insertable and removable ceiling panels (blocks or tiles) are structurally incapable of supporting heavy fixtures, such as lighting fixtures, and the like. Therefore, only a limited number of available fixtures are of sufficiently low weight to allow usage with such ceilings, a flush-mounted or recessed fixture of light weight usually being employed in place of a single ceiling panel. Therefore, the art has previously provided apparatus for suspending junction boxes in a suspension ceiling, such as disclosed by LoNigro, in U.S. Pat. No. 3,597,889, and by LeManquais, in U.S. Pat. No. 1,966,451, the structures disclosed therein allowing the mounting of lighting fixtures and other appliances of varying weight, size and shape. It is, therefore, to be understood that the concept of providing structure in a suspended ceiling framework capable of providing balance support means for electrical lighting fixtures is not new in the field of endeavor under consideration.
Description of further prior art structures adaptable to similar purpose is provided in U.S. Pat. No. 3,597,889, the disclosure of which patent is incorporated hereinto by reference.
The present invention provides structure similar to that disclosed in U.S. Pat. No. 3,597,889, the structure so disclosed being improved by forming the straight, substantially flat-faced median portion of the supporting bar with twisted portions near proximal end portions thereof to add strength and torsional stability to the bar. In effect, the median portion of the prior art supporting bar, major planar surfaces of which are substantially horizontally disposed in said prior art supporting bar, are turned 90 degrees so that the major planar surfaces of the bar are substantially vertically disposed, the median portion of the supporting bar remaining aligned in a substantially straight line with the proximal end portions of the bar.
The invention, therefore, provides a prefabricated adapter apparatus which comprises a length of flat-faced strap iron which is of one-piece construction and provides a substantially rigid supporting bar. This bar has a median portion, the axis of which is pivoted or twisted relative to the end portions thereof as aforesaid, the bar being sufficiently rigid to accommodate a slotted hanger clip, that is, a clip which is fastened to or otherwise carried by a slotted top wall of a conventional junction box. The respective end portions of the strap iron or bar are provided with downwardly offset bent portions. Each bent portion is L-shaped and has a horizontal portion united with a right angularly disposed downwardly opening U-shaped terminal end portion which defines a bar mounting and attaching hook. The respective hooks are fitted over the vertical flanges of customary T-irons which are employed in a ceiling frame. The outer leg or bill portion of the hook is equipped with a setscrew which permits the hook to be securely anchored. In particular, the body portion of the strap iron or bar is of a predetermined length and is straight from end to end, said body portion serving to accommodate a conventional cup-shaped junction box along the median portion thereof, particularly a junction box which has a top wall provided with a U-shaped clip. The clip has opposed spaced parallel legs which project upwardly through slots provided in the top wall of the box. The projecting portions of the legs have registering slots which are adapted to slidingly receive portions of the supporting bar medially of its length in a manner to permit a junction box to be shifted to assume and maintain a predetermined position.
It is, therefore, an object of the present invention to structurally and functionally provide improvement to prior art lighting fixtures support apparatus, particularly apparatus such as disclosed in U.S. Pat. No. 3,597,889, and to provide a junction box suspension unit capable of supporting loading encountered in the hanging of lighting fixtures and similar appliances.
These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.